Phenylalanine hydroxylase

Phenylalanine hydroxylase (PAH) is found in the liver where it catalyses the hydroxylation of phenylalanine to tyrosine. This is the first step in the oxidative degradation of phenylalanine. Mutations in PAH leading to a decrease in enzyme activity results in the disease phenylketonuria, where phenylalanine is converted to phenylpyruvate. Phenylpyruvate is toxic and leads to mental retardation. PAH is also found in some bacteria, but only PAH from the bacteria Chromobacterium violaceum and Colwellia psychrerythraea have been characterised. The bacterial PAHs are monomeric and do not contain a regulatory domain. All the aromatic amino acid hydroxylases are believed to have evolved from common ancestor containing only the catalytic domain. Structures available of phenylalanine hydroxylase abbreviation for domains r regulatory domain c catalytic domain t tetramerization domain

Additional Resources
For additional information, see: Amino Acid Synthesis & Metabolism